The NHTSA says car seats reduce fatalities by 54 percent. But it draws the comparison with children sitting in cars unrestrained and not using a seat belt.

A popular argument against using seat belts is that they do not fit kids properly. But "SuperFreakonomics" authors Steven Levitt and Stephen Dubner claim that for children older than 2. there is no significant difference in the fatality rate between car seats and seat belts, 18.2 percent versus 18.1 percent respectively.

Levitt and Dubner commissioned their own crash test and found that for children 3 and 6 years old, seat belts work just as well as car seats.

"We're not telling people not to wear them," Levitt told "Good Morning America." Only that car seats are no safer than seat belts, Levitt said.

For 2-year-olds and younger, Levitt said definitely "do not throw out the car seats."

"The problems are often being addressed by solutions that are often not the best solutions," Dubner said. "If safety is the primary concern, there are better options."

But critics say that Dubner and Levitt's claims are wrong and misleading.

"It is simply false to suggest that seat belts are as good as car seats or booster seats at protecting young children in the event of a crash," Dr. Dennis Durbin at Children's Hospital of Philadelphia, said.

Critics Blast 'SuperFreakonomics' Findings

Durbin said that between 2000 and 2008 the number of children using car and booster seats have increased dramatically while the number of children killed in automobile crashes has declined by 45 percent.

"While crash tests serve a very important role in child restraint design, they only tell part of the story," Arboghast said. "The child crash test dummies don't have a way of presenting injuries to the belly. These are the second most common injury for children in seat belts."

CLICK HERE to read a statement from the Center for Injury Research and Prevention.